The chemical modification of any substrates is a critical success factor in chemical, biological and material sciences, engineering and applied technology. The primary method for such a chemical modification may include a surface treatment chemistry and other physicochemical techniques, whereby desired chemical and/or physical properties are created on non-functional substrates. Molecular species serving this purpose mostly have chemical function groups on both ends, in which one end is bound to given substrates and the other end offers chemical functionality to the substrate surface.
The Korean patent laid-open No. 10-2003-0009732 describes an organic molecular substrate the surfaces of which are coated with a multiplex amino ethyl molecular layer. This patent discloses an organic polymer substrate and a preparation method thereof, wherein a substrate formed of various organic polymers or oligomers containing nucleophilic functional groups react with aziridine or a derivative thereof, thus forming a multiplex amino ethyl molecular layer which consists of a high density polymer, whereby a physiochemical property can be changed. This technique discloses a method for modifying the surface of a substrate in such a way to react an aziridine compound with an organic polymer substrate.
The substrates available for conventional surface modification chemistry, however, are highly limited. This in turn causes the following issues for chemical modification of a substrate; (1) chemical specificity between surface modifying chemical species and substrates is required; (2) the substrate size/shape is often limited; (3) instrumentation is often required; (4) multi-step procedures, resulting in the lowered success rate and reliability, are required.
As a solution to this problem, a substrate-independent surface modification technique was invented, in which dopamine or other similar compounds containing both of catechol and amine functional groups was used under an alkalinene solution. The method employs a biomimetic mechanism of mussels to generate a natural surface-independent adhesive. Mussels attach to virtually all types of inorganic and organic substrates, including even adhesion-resistant materials such as Teflon (aka polytetrafluoroethylene; PTFE). With the aforementioned techniques, various surface modification applications could be made.
The laid-open U.S. Pat. No. 8,541,060 describes a multifunctional coating and an application thereof, wherein the surface can be modified surface-independently. This patent discloses a coating method wherein the surface can be modified in such a way to contact a dopamine or a dopamine-like compound with a substrate in an alkaline solution using a surface modifier.
The laid-open U.S. Pat. No. 8,999,452 describes a multifunctional coating and an application thereof. This patent discloses a method for modifying a substrate surface in such a way to contact a surface modifier, for example, dopamine, with a substrate in an alkaline state.
The aforementioned dopamine-based technologies may have the following problems in terms of technology. (1) This technique can be carried out only under an alkaline condition. Most of experiments are being carried out on a trisaminomethane buffer solution of 10 mM pH 8.5. This value is close to pKa (dissociation constant) of the dopamine, which is around pH 9. For this reason, reactivity might not be controlled as intended. (2) Two different reaction groups of hydroxyl groups and amine groups of dopamine compound may make it hard to evenly control surface functionality. (3) It is hard for amine groups to exist a lot due to a chemical structure, so the performance of the following applications which could be carried out based on the modification of the amine structure, may be limited.
In order to resolve the aforementioned problems, a substrate-independent surface modification method is required.